1. Field of the Invention
This invention generally relates to cordless pointing devices, and more particularly, to a cordless pointing device having a very thin-shaped operation unit to be operated by a user.
2. Description of the Related Art
In recent years, a pointing device has been used as an input device installed in an information device such as a personal computer. The pointing device is used for moving a pointer shown on the display screen so as to select information and give an instruction to the computer. There are various types of pointing devices such as track pad, track ball, and mouse.
Japanese Patent Application Publication No. 2002-318661 (hereinafter referred to as Document 1) discloses one of the aforementioned pointing devices. Document 1 describes a pointing device having an information display unit, a sensor, and a control unit. The information display unit displays information and the pointer for selecting the information. The sensor senses an optical image of a finger and detects a movement of the finger. The control unit moves the pointer based on the movement of the finger detected by the sensor. According to the pointing device disclosed in Document 1, the necessary information can be selected by moving the pointer displayed on the information display unit with only one finger.
Among the above-mentioned various types of the pointing devices, the track pad or the track ball can be incorporated into, for example, a keyboard, and does not take up much space even after the installation of the pointing device. However, a problem arises in user-friendliness, for example, the operator is required for getting used to the pointing device.
The pointing device described in Document 1 has an excellent user-friendliness when manipulating the pointer with one hand and holding a mobile terminal such as a mobile telephone in the other hand. In addition, the pointing device described in Document 1 does not take up much space even after the installation of the pointing device. However, when manipulating the pointer displayed on the display screen of a notebook PC, for example, there arises the same problem as the above-mentioned track pad or track ball in that the operator is required for getting used to the pointing device and the operation of the pointing device is not user-friendly. Moreover, the pointing device described in Document 1 reads optical images of a fingertip and then moves the pointer. It is to be noted that the fingertip cannot be focused on depending on the user's operation. If so, the optical image cannot be acquired completely.
In contrast, a mouse is user-friendly and easy to use. Therefore, the mouse is employed in various information terminal devices represented by the personal computer. In these years, a light-emitting device and a light-receiving device are installed onto a main body of the mouse, which is known as an optical mouse, the pointer can be moved according to a moving direction of the mouse. Referring to FIG. 1, an optical mouse 52 includes an optical sensor 52a having the light-emitting device and the light-receiving device. The mouse 52 is manipulated on a desk 53 or the like. The optical sensor 52a receives a reflected light as shown by an arrow 54, senses a movement of the mouse 52, and reflects the movement in the pointer. Additionally, a wireless mouse has come into the market, and operability has been improved more than before. The wireless mouse is not connected with a code to the information terminal device such as a personal computer.
A console drawer is one of the information terminal devices. Referring to FIG. 2, a console drawer 50 includes a display screen 55 that can be opened and closed like a notebook PC. The console drawer 50 can be mounted on a rack 51 having multiple drawers like a chest of drawers. The console drawer 50 includes a keyboard 56 and a mouse 52. The operator manipulates the mouse 52 on a space in the vicinity of the keyboard 56. Here, the display screen 55 that can be opened and closed employs a liquid crystal display, in many cases. However, referring to FIG. 4, it the mouse 52 is placed in the vicinity of the keyboard 56 and the display screen 55 is mistakenly closed, the mouse 52 might damage the liquid crystal display of the display 55. Furthermore, the mouse 52 needs a certain space and height. In particular, the wireless mouse device includes a power supply such as a battery in the main body of the mouse, and thus there is a limitation of reducing the thickness of the mouse.